Containerized cargo has become ever more popular in recent years as a very efficient means of shipping a multitude of items or goods. Standard size containerized cargo enclosures are utilized on special ships that hold a numerous of these types of containers in a stacked arrangement on special container ships. These containers are carried both within the hull or container hold of the container ship and above the deck of the container ship with the container being of substantially rigid construction to support one another in a stacked arrangement while protecting the items within the container. With the ever increasing importation and exportation of items between different countries, containerized cargo has become one of the more significant methods of shipping. Frequently, shipping companies give transportation cost discounts to items that are designed to fit within the containers, as a container simplifies the loading and unloading of ships, the containers are also adapted to substitute as a semi truck trailer and can fit on railcars, so the same container can ship by sea or overland by truck or rail.
Given that containerized cargo has proven its utility in the shipping industry, there have been ancillary uses of containerized cargo enclosures, such as for long-term storage and protection of items, temporary offices at field sites, and for creating a small work area for light industrial uses. A typical container is constructed of carbon steel with a box or rectangular stock for a framework, the container also has having a corrugated sheet metal walls and top, with a stronger frame component on the bottom portion that allows for lifting lugs or hooks to be placed, or fork lift tangs from forklifts to be inserted for moving the enclosure. As previously mentioned, the containerized cargo enclosures are also configured to be stackable upon one another and also the bottom portion is adapted to attach to either a and semi truck bed or a rail car bed. When the containerized cargo container is used in its primary purpose for the hauling of various items, there is usually a door at one end of the container that opens for the items to be manually loaded and unloaded from the container. Typically, large items are pushed into the container or loaded inside the container by the use of a forklift truck with the large items being removed from the container in the same manner. Thus, loading and unloading large items from a container is normally a fairly simple operation not consuming too much time. However, when the containers are loaded with many small items that are not necessarily light in weight, being within the 50 lb. to 1,000 lb. range, loading and unloading the container can become an inefficient operation due to the manual handling of these numerous items.
When using a container for numerous small items that may or may not be heavy, the situation is much the same as a conventional semi truck trailer, where it has been recognized that having a special purpose built-in crane hoist apparatus within the cargo container can be very beneficial and useful in reducing the amount of time it takes to load and unload numerous small items. U.S. Pat. No. 5,062,760 to Samaniego discloses one such material handling system that uses a series of perpendicularly oriented frames and a winch cable assembly. The winch is able to move to any location within the enclosed van or trailer and also can extend a certain distance from the rear of the trailer thus allowing various items of cargo to be transported from a location within the enclosed trailer to a location outside of the trailer. The material handling system is attached to the interior of the cargo compartment adjacent to the roof portion. A similar system to is disclosed in U.S. Pat. No. 5,338,147 to Kucharczyk et al. and U.S. Pat. No. 4,297,071 to Dunbar that attempt to reduce the amount of head room consumed by the crane apparatus as compared to Samaniego. Both Kucharczyk et al. and Dunbar recognize one of the problems in the art in using this type of crane is that the normal crane construction of what is called the trolley or bridge type of crane dictates that the frames are mounted one below the other with the resulting winch carriage being mounted below the lowest frame. The purpose for this traditional crane construction is to maximize the lifting load capability of the crane by keeping the load directions in a specific beam axis that have the most beam strength. Also, this type a crane in its usual mounting location, which would either be a warehouse or factory, typically has extra high ceilings that can allow for this type of crane construction, which consumes a fair amount of vertical space or headroom. When utilizing a crane hoist apparatus within a cargo container, however, this consumption of vertical space or headroom is a negative factor in mounting a specialized crane apparatus inside of a cargo container, and thus design modifications need to be made to the crane frames and winch to minimize the vertical distance or headroom consumed.
However, when a crane is designed to absolutely minimize the vertical distance consumed or headroom there are compromises of the cranes weightlifting capacity when the frame beams are loaded in the same horizontal plane that induces a torsional moment component into the beam loading, wherein any given beam has considerably less strength when placed in a torsional loading state as opposed to a straight vertical load state. Thus, to minimize the consumption of vertical space or headroom there has to be a number of considerations in the slidable engagements between the frames and the carriage winch, in addition to a more difficult task of calculating the much reduced load carrying capacity of a crane constructed in this manner. What is needed is a crane hoist apparatus that is specifically designed to permanently mount in a containerized cargo enclosure with the crane hoist apparatus completely contained within the enclosure and with a crane having the capacity to extend outside or to the exterior of the enclosure to move items both within the enclosure interior and to and from the exterior of the enclosure. Also, what is needed is a crane hoist apparatus that consumes no more vertical space or headroom than the frame itself including all the slidably engaging frames that form the bridge or trolley including the carriage winch assembly. This type of crane hoist apparatus would act to absolutely minimize the loss of interior volume in the containerized cargo enclosure due to the installation of the crane while providing at the same time the efficiency and convenience of being able to move a number of items within and to the exterior the enclosure in a speedy manner.